1. Field of the Invention
The present invention relates to drywall finish trim devices typically utilized in finishing a drywall installation at a corner joint or other terminus.
2. Description of the Prior Art
Drywall, sometimes also referred to as wallboard, is a staple in the construction industry as an economical alternative to plaster for forming the interior walls and ceilings of rooms in residential, commercial, and industrial buildings. The materials used in drywall construction include gypsum board, plywood, fibre-and-pulp boards, and asbestos-cement boards. The large, rigid sheets are fastened directly to the frame of a building with nails, screws, or adhesives, or are mounted on furring (strips of wood nailed over the studs, joists, rafters, or masonry, which allow free circulation of air behind the interior wall). A significant advantage of drywall construction is that the craftsman is not required to delay his or her finish work while the plaster spread over the interior support structure dries. Wallboard is manufactured in both finished and unfinished forms, and in its finished form may be faced with vinyl or other materials in a variety of permanent colors and textures so that they do not need to be painted when installed.
Drywall construction allows the drywall hanger to easily cut the panels to many different shapes and sizes for assembly and hanging from the building frame. However, workmen face a challenge in finishing drywall panels at an edge or corner. It is very difficult, if not impossible, to cut the edges of such panels with the precision, straightness, and smoothness required to abut the edges of adjoining panels in a sufficiently straight corner to provide an aesthetic finish. Additionally, cut edges expose the soft, raw cores of the drywall panels, thus requiring some sort of covering or treatment to afford a finished appearance.
As a result, several different devices and techniques have been developed in effort to produce a structurally sound corner or other joint that exhibits a smooth and seamless intersection. Devices proposed to achieve this result include drywall tape, trim and corner beads. Conventional drywall tape may be applied to the joints and edges of abutting panels to be covered by wet joint compound that is feathered and smoothed to cover the newly created seams. When the joint compound has dried, the tape and drywall can be sanded, painted, covered, or otherwise finished in whatever manner is desired. Great deal of skill is required, however, to apply and form the joint compound to create a sufficiently straight intersection that will exhibit, when taped and sanded to a finish, no evidence of scuffing and tearing in the tape.
In light of the limitations on use of drywall tape to trim a joint, trim strips or corner beads are often utilized to cover a joint and produce a seamless and aesthetically pleasing edge trim or intersection at the corners of drywall panels.
Such trim strips may take many different configurations and are typically in the form of an angle corner bead having diverging flanges or may be, for instance, a J strip to cap the edge of a dry wall panel. For the purposes of this invention, the particular configuration is not critical and use in conjunction with numerous different configurations is contemplated. For instance, the trim may be flat or configured with any one of a number of well known configurations, including corner trim with perpendicular flanges, corner trim with a rib formed at the juncture of the flanges defining a bead, flanges angled at 135° to one another, those configured with somewhat of a Z shape, those with soft line or rounded corners, and those with offsets or other configurations traditionally used in the trade and known to those skilled in the art.
One common feature of many of the trim strips or corner beads currently available is the use of a rigid or semi-rigid core that caps the drywall corner joint to provide support and to prevent the drywall from being chipped or cracked along the otherwise exposed edges of the panels. Typical materials known and used in the art for such cores include galvanized steel, aluminum, plastic, and sometimes stiff, thick paper. A disadvantage of these cores is that they must be anchored in some way as by nailing, screwing, or otherwise fastening to the drywall panels. A further disadvantage of such cores is that the drywall finishing compound applied to the corner joints to complete the assembly may not readily adhere to such rigid and semi-rigid core materials or easily conceal nail or screw heads, making it difficult to cover, sand, paint or otherwise finish out the corner joint in an aesthetically-pleasing manner.
To enhance the function and finished appearance of drywall corner joints configured with corner beads, efforts have been made to provide such beads with an exterior covering of some other material such as paper or fabric to facilitate both installation and application of the joint compound to the exterior surfaces thereof. The challenge is to provide such an exterior covering that is substantial enough to secure the inner core in position while being thin enough to create a smooth transition between the cover and the underlying drywall. One bead developed to address some of the problems with the prior art is a corner bead with a metal core, covered on its exterior with a paper cover which projects beyond the opposite lateral edges to form flexile, flaps to be secured in place as by nailing and embedding in joint compound. I have discovered that such flaps often fail to securely anchor the corner bead device in place thus allowing for shifting of the bead relative to the drywall thereby producing an irregular appearance.
It has been common practice to form such flaps with small holes for communication of moisture during the curing process for the joint compound. Oftentimes, such holes are formed by punching chads from one side of the flap often leaving one side of the chad attached. Consequently, some of the attached chads end up acting as flaps which close over the holes upon installation thus serving to block communication of joint compound through the respective chad holes.
It has also been discovered that prior art corner beads suffer the shortcoming that such flaps are often wavy throughout their length, making it difficult to effectively cover the flap material with a smooth layer of joint material to adequately securely anchor them in the joint compound.
Because these features have not been optimally satisfied in a single drywall bead design, there still exists a need for such a finishing bead that addresses each of these challenges. The present invention is directed to just such a drywall bead.